This invention relates to liquid sealant application and is particularly concerned with a sealant spray applicator system and to a method for applying liquid sealant in holes of a structural member prior to installing fasteners in such holes, particularly employing such sealant spray applicator system.
In the wet installation of rivets and lockbolts for fastening structural members, particularly in the aircraft industry, a machine, commonly known as a "Drivematic", first drills a hole in the structural parts to be fastened, and when this is completed, the machine installs a fastener, such as a rivet or lockbolt. However, if such fastener installation requires a sealant to be placed in the hole first, a sealant applicator applies sealant in the hole by means of a tip or nozzle which is placed directly in contact with the hole. In this position, a valve is opened and the liquid sealant is squirted into the hole.
However, the use of such conventional type sealant applicator systems has a number of disadvantages. In the first place, generally in order to apply sufficient liquid sealant to satisfy the requirements, an excessive amount of sealant is applied. Thus, conventional sealant spray applicators are unable to provide the thin film of sealant application to holes particularly required for automated lockbolt installation. Further, as a result of an excessive amount of sealant application, parts of the sealant applicator at and adjacent to the nozzle become coated with the sealant, and there is also a tendency for constant dripping of liquid sealant from the nozzle. The result is that these parts of the sealant applicator require excessive cleaning. Further, conventional sealant applicators require an inventory of nozzles or tips for each hole diameter.
One object of the present invention is the provision of an improved sealant spray system and a method employing a sealant spray for application to holes of a structural member prior to installing fasteners in such holes.
Another object is to provide an improved sealant spray system and method employing same which reduces sealant waste and part clean-up requirements.
A particular object is the provision of means and a method for thin film sealing application for automated rivet and lockbolt installation.
Yet another object is to provide an improved sealant spray applicator system and method for applying liquid sealant readily to holes of varying diameters without changing nozzles or tips, as in the case of conventional sealant applicators.